Prior to my invention, thick molded parts of fibrous-ply-reinforced resin were subject to having internal cracks, voids, or poor lamination.
U.S. Pat. No. 4,404,261, issued to John L. Canning and John F. Kay on Sept. 13, 1983, discloses molding of multiple plies of sheet molding compound reinforced with chopped glass roving, each ply having its own formulation with respect to polymerization initiating temperature, and the center ply having the lowest such temperature with successive plies in each direction having progressively higher such temperatures, whereby all plies begin to cure about at the same time from the heat of the mold.